Productivity may be important to printers. Improving image quality at low number of passes may be a way to succeed. One challenge when printing at low number of passes, for example at a number from 1 to 4, may be the line banding caused by paper advance errors.
Some printing systems may use an ink-jet for transferring colors to a print. Some printing systems may use electrostatic forces for transferring colors, for example by a dry toner powder or a liquid toner.
The examples and description below make reference generally to ink-jet printing systems. A color of the printing system may be printed by a set of nozzles. The set of nozzles may be associated with the color(s) to be printed. Each set of nozzles may be part of a separate printhead. According to other examples a printhead may comprise two or more sets of nozzles and may be to print two or more colors associated with the nozzles. Explanations set forth below may refer to a misalignment between printheads but may be transferred without limitations to a misalignment between a set of nozzles.
Printing systems may use a carriage comprising a number of printheads to transfer drops of ink to a medium. For example, the carriage may comprise four printheads, such as cyan, magenta, yellow and black. Other carriages may comprise one printhead, for example, black. Other carriages may comprise a larger number of printheads, for example a half tone cyan and/or a half tone magenta. However, the techniques described herein may also apply, with appropriate modifications, to any other printing systems that use a different number of printheads or that print any type of printing fluid such as liquid electro photographic (LEP) printing systems or dry toner printing systems.
Colors may be obtained on a medium, for example, based to a subtractive color system and based on printing a plurality of color planes on top of each other. When considering a carriage comprising printheads to obtain a printed color on a medium based on an overlay of basic colors of a printer, those printheads may be aligned with respect to each other such that on a location of the print all colors are available. For example, a printhead (pen) alignment may be triggered.
Examples described herein provide a method for printing an image by manipulating image data related to a color plane of an image. A specific color plane may refer to a specific color. The specific color may be a basic color of the printer or a mixture of basic colors. A color plane may refer to a position of the specific color in the image. The color plane may also refer to an area or plane in which the specific color may be printed on the printer. An image may be separated into a two or more color planes. Each color plane may comprise information related to the image, simplified the image in the specific color. Shifting color planes with respect to each other may allow for obtaining images shifted with respect to each other.
According to an example, image data may be obtained by using a processor. The image data may comprise first image data defining a first color plane of the image. The image data may comprise second image data defining a second color plane of the image. The image data may be manipulated with the processor such that the second color plane is shifted relative to the first color plane in a medium axis direction of a printer. The manipulated image data may be printed with the printer.
A misalignment between the printheads of the carriage of the printer may result in a further shift of the color planes with respect to each other. The further shift may be opposed with respect to the shift obtained by using the processor. The shift of the color planes obtained by manipulating the image data may be performed such that the manipulation at least partially compensates for the shift of the color planes obtained during printing.
According to another example, the image data may comprise third image data defining a third color plane of the image and may comprise fourth image data defining a fourth color plane of the image. The image data may be manipulated such that the third color plane and the fourth color plane are shifted relative to the first color plane in the medium axis direction of the printer.
Other examples described herein may provide a method for printing an image comprising a separation of the manipulated image data to obtain a first manipulated image part and a second manipulated image part. The first and/or the second manipulated image part may comprise a size along the medium axis direction of the printer which may correspond to a size of the image that may be printed during one pass of the carriage.
Other examples described herein may provide a method comprising separating the image data to obtain a first image part and a second image part which may correspond to the size of the image that may be printed with one pass of the carriage. The image data may be manipulated such that the second color plane and the first color plane may be shifted relative to each other for each of the image part to obtain manipulated image parts. The manipulated image parts may be printed.
Other examples described herein may provide a method in which an image may be printed with a printer by using a first printhead and a second printhead of the printer. A deviation of the printer may be determined, wherein the deviation may indicate an offset of nozzles of the second printhead relative to nozzles of the first printhead. An information may be provided to a further printer, the information indicating the determined deviation. The provided information may be used by a further printer for shifting a second color plane relative to a first color plane based on the determined deviation.